The present invention relates to an adsorbent comprising a substantially syndiotactic styrene polymer, more precisely, to such an adsorbent comprising a substantially syndiotactic styrene polymer, of which the pore size is equivalent to the molecular size of an organic compound to be adsorbed by it.
For removing an organic compound such as a hydrocarbon compound, fuel, solvent or the like, from gases or liquid that contains it, heretofore employed is a method comprising feeding a gas or liquid into an adsorption column filled with an adsorbent such as zeolite, activated alumina or the like, followed by making the organic compound adsorbed by the adsorbent to thereby remove the organic compound from the gas or liquid. The organic compound thus adsorbed by the adsorbent in the method is desorbed from it by feeding water vapor or the like into the adsorption column, expelled from the column along with the water vapor, and recovered and recycled.
However, the inorganic porous substance used in the method has some drawbacks in that it is limited in point of its crystal morphology and therefore the size of the organic compound capable of being adsorbed by it is limited, and in that its structure could not all the time correspond to the size of a specific organic compound which is intended to be adsorbed by it and therefore it cannot selectively adsorb the specific compound from a mixture of compounds having similar molecular morphologies.
In case where the device as above is difficult to install in printing factories, painting factories, etc., the solvent used in such factories is not removed and recovered satisfactorily, and a simple method of removing and recovering organic compounds is desired.
Also desired is a method of efficiently removing and recovering impurities from liquids, not requiring distillation.
The present invention is to provide an adsorbent capable of selectively and efficiently adsorbing an organic compound existing in gases or liquids.
We, the present inventors have assiduously studied to attain the object as above, and, as a result, have found that an adsorbent produced by forming a complex of a syndiotactic polystyrene with an organic compound followed by shaping it and removing the organic compound from the shaped article through evaporation can selectively and efficiently adsorb the organic compound. On the basis of this finding, we have completed the present invention.
Specifically, the invention provides the following:
1. An adsorbent comprising a substantially syndiotactic styrene polymer.
2. The adsorbent of above 1, which is produced by forming a complex of a substantially syndiotactic styrene polymer with at least one selected from an organic compound and a solvent of which the molecular size is equivalent to that of the organic compound, followed by shaping the complex, and thereafter removing the organic compound or the solvent from the shaped article without substantially changing the crystal structure of the styrene polymer in the shaped article.
3. The adsorbent of above 1, which is produced by dissolving or swelling a substantially syndiotactic styrene polymer in an organic compound having an affinity for the polymer, followed by shaping it, and thereafter removing the organic compound from the shaped article.
4. The adsorbent, which is produced as above 2, wherein the shaping the complex is performed by a melt-casting process.
5. The adsorbent, which is produced as above 2 or 3, wherein the removing the organic compound is performed by evaporation under reduced pressure.
6. The adsorbent , which is produced as above 2 or 3, wherein the organic compound is an aromatic compound.
7. The adsorbent of above 6, wherein the aromatic compound is at least one selected from benzene, toluene, xylene, chlorobenzene, bromobenzene, dichlorobenzene, and trichlorobenzene.
8. The adsorbent of above 1, which is for adsorbing an organic compound.
9. The adsorbent of above 1, which is produced by forming a complex of a substantially syndiotactic styrene polymer with at least one selected from an organic compound and a solvent of which the molecular size is equivalent to that of the organic compound, melt-spinning the complex into fibers after or while the complex is formed, and thereafter removing the organic compound or the solvent from the fibers without substantially changing the crystal structure of the styrene polymer in the fibers.
The complex of a substantially syndiotactic styrene polymer with an organic compound is meant to indicate that the styrene polymer therein carries the organic compound in its crystal structure with keeping its crystal structure in some degree.